With regard to elevator systems, known in the art are call-giving systems wherein a passenger gives elevator calls by means of a call device or identifier device in his/her possession, which device is e.g. a passive RFID (Radio Frequency Identifier) or an active terminal, often provided with pushbuttons, in which terminal the unique identifier code of the terminal is recorded. For reading the data of a call device the elevator system must be provided with reader devices, into the operating range of which a passenger must take his/her call device. The reader devices of call devices that are remotely read can be disposed e.g. in elevator lobbies at a distance from the elevators, whereas the reader devices of call devices that are read from close range are often disposed in connection with conventional destination call panels. On the basis of the data received from a call device, the elevator system can generate a personal destination call to the floor desired by the passenger. Solutions are also known in which passengers are identified from a fingerprint or from some other bio-identification instead of the data read from call devices. Often access control is also connected to the aforementioned solutions such that for each passenger a personal service profile is determined for the elevator system or for a special access control system, in which service profile data about those floors to which the passenger has an access permit is recorded.
A number of drawbacks are, however, connected to the prior-art solutions described above. Systems based on bio-identifiers are often complex and expensive because powerful computer apparatus is needed for processing information in them in order to achieve a reliable and fast identification. A crosstalk problem, on the other hand, wherein a call device in the possession of a passenger is simultaneously detected by two or more reader devices e.g. disposed on different floors, is connected to remotely-read devices. This easily leads to the generation of erroneous elevator calls or other service requests. To minimize the crosstalk problem, reader devices must be located in a building with particular care and accuracy, which of course raises costs. Remotely-read call devices can produce useless elevator calls also when a passenger arriving in an elevator lobby does not want to use the elevators but instead calls into an elevator lobby for some other reason. The use of call devices to be read from close range, on the other hand, requires that the passenger takes out his/her call device and takes it close enough to the reader device, which is impractical and slows down arrival at destination. In prior-art solutions the number of different types of service requests is generally limited to one service request or to only a few service requests, e.g. to just giving a destination call to the default floor of the passenger. The problem can be partly solved by providing a call device with selection pushbuttons, by means of which a passenger can make choices between different service requests. Adding selection pushbuttons, however, easily makes a call device large in size and awkward to use.